People that are farsighted due to old age or people that are weak-sighted may sometimes use reading glasses or magnifying glasses for visually recognizing characters more easily. However, the use of reading glasses or magnifying glasses is troublesome. Further, reading glasses and magnifying glasses are inconvenient to carry.
Owing to the wide use of smartphones in recent years, electronic devices such as smartphones are equipped with a function of a magnifying glass or a reading glass. This character enlarging function can be implemented in the form of, for example, photographing an object with a camera of a smartphone and displaying an enlargement of a predetermined portion of the photographed object.
Further, Patent Document 1 proposes a technique of detecting a target object from an image displayed on a screen (e.g., face of person) and determining an expansion rate and display area for enlarging and displaying the target object. Then, the target object is enlarged and displayed according to the determined expansion rate and display area.